I have an AC 3 phase motor and need to hook up a logger for measuring current, among other things.
I am looking up the current transducers and see that there are some designed for three phase with three holes to run the wires through and others that have one opening that would read one leg. (top middle picture vs. bottom left)
Is having all three legs connected necessary or would having one leg enough to have a good reading?
A three phase current transformer is useful for situations where you might have an unbalance load, i.e., the phase currents are not equal. In a motor, you can expect the phase currents to be nearly identical so a single current transformer should suffice in most applications.